Change data template on key press and send key to template

Question

I have a custom control which is rendered as a cell in a data grid (Infragistics). All cells are displayed with its read-only template. The cells can be selected (provided by Infragistics).

Now if the user press for example "3" I change the template from read-only to an edit template. Which works fine.

The edit template contains a text box that should have the focus afterwards and also receive the keypress, eg. 3. The problem is that at the time I receive the keypress and change the template, it is not rendered yet of course.

Control

public class Cell
{
  //dependency properties
  public DataTemplate ReadOnlyTemplate;
  public DataTemplate EditTemplate;
  public DataTemplate CurrentTemplate;

  OnPreviewKeyDown()
  {
    CurrentTemplate = EditTemplate;
  }
}

Xaml

<Style TargetType="{x:Type local:Cell}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:Cell}">
                <Border BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                    <ContentControl HorizontalAlignment="Stretch"
                                    VerticalAlignment="Stretch"
                                    Content="{Binding DataContext, RelativeSource={RelativeSource Self}}"
                                    ContentTemplate="{Binding CurrentTemplate, RelativeSource={RelativeSource TemplatedParent}}" />
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

I cannot use OnApplyTemplate because the template is rendered directly within the cell but in one of the children.

Here are some ideas I came up with to solve

collect the keypress events until the template is rendered and then focus the textbox in the edit template and push the keypress events to it
"somehow" put the rendering in a priority dispatcher and wait "sometime" until it is rendered and then do the GUI actions

Can someone point me in the right direction?

Have you tried to use `DataTemplateSelector` [class](https://docs.microsoft.com/en-us/dotnet/api/system.windows.controls.datatemplateselector?view=netframework-4.8)? — Pavel Anikhouski, Sep 24 '19 at 09:01
E.g. set the `ContentTemplateSelector` property for cell and bind it to textbox text — Pavel Anikhouski, Sep 24 '19 at 09:08

score 1 · Answer 1 · answered Sep 24 '19 at 14:28

I ended up with the following

cell.Dispatcher?.BeginInvoke(DispatcherPriority.Render, new Action(() => OnCellEnteredEditMode(cell)));

private static void OnCellEnteredEditMode(Cell cell)
{
  //traverse through the visual tree of the cell down to the first item which I can set to focus to
  //use win32 API to send key press
}

How to simulate a Ctrl A + Ctrl C using keybd_event

Change data template on key press and send key to template

1 Answers1